I was down in Manchester today. I took the redeye train to Manchester Oxford Road (MCO), with the Brompton folded up next to me in gap between the luggage rack and my seat. I can confirm that navigating across central Manchester on a bike in morning rush hour using the route display on a Garmin Edge 200 is possible, albeit slightly stressful.
On my way back I was accosted outside MCO by a woman advertising their new Bike and Go scheme. She looked at my Brompton and said hopefully 'Here's a leaflet, if you ever forget your Brompton'...
Anyhow, there's a great big rack of red bikes outside Manchester Oxford Road station, should you be going that way and need to hire one. You need to register first, I believe.